fc? 


Circular  No.  6,  Second  Series 

United  States  Department  of  Agriculture, 

DIVISION     OF     KNTOMOLOGY. 


THE  MEXICAN  COTTON-BOLL  WEEVIL. 


.  I  HlkOHwmUl   i/i  ii  nili-    Bob 


N I  i:\i      U'PI    m;\n<  1      \\i>    Ml   illin>    (ll     WORK. 

This  i unci- i  i>  ;i  small,  l; r. i \  i-U  w rc\  1 1,  of  the  shape  and  general  appearam  e  show  n 
I  a.  and  measuring  a  little  less  than  a  quartet  ol  an  inch  In  length,  which  is 
found  m  cotton  Belda  throoghonl  the  season,  pun<  raxing  and  laying  its  eggs  in  the 
squares  and  bolls.  The  larva?,  of  the  shape  and  appearance  shown  at  Fig.  1 
measuring  a  little  ovei  three-eighths  of  an  inch  in  leugtb  when  lull  grown,  lire 
within  the  bnds  and 
bolls  and  feed  upon 
their  interiorsnbstance. 

The    sqnam    attacked  V   \    m   /   ^  'A*\ 

nsnally  drop,  imt  most  f       vRv/       l 

remain  upon  the  plan!  ^^S       ^  ' 

and  become  Btnuted  or 
dwarfed,  except  late  in 
tln>  season,  when  they 
either  dry  or  r<>r . 

1>1-I  l:  I  Hi    I  b>s 

The  species  is  orig- 
inally Mexican,  and  for 
man  baa    been 

fonnd  in  the  region 
around  Monetae  a,  iu  the 
Btate  of  Coahnila.     Krom  1856  to  18  '1  in  thai  region  that  rotton  plant- 

ing was  abandoned.     It    appeared  in   the  vicinity  of  Matamoroa  some 

d  the  river  to  Brownsville,  and  within  the  last  two  or  three  years  has  spread 
north  into  the  coontrj  aronnd  Ban  Diego,  Alice,  and  Beeville,  Tex.,  and  threatens 
to  spread  throughout  the  cotton  growing  regions  of  rexas,  if  not  toother  S 
The  accompanying  map  shows  the  distribution  of  the  inseel   it  the  close  ol  tl 

1 


•  va — oil 


sou  of  1#!>l,  the  cross-barred  portions  indicating  the  regions  more  or  less  severely 
damaged,  and  the  single-lined  portion  the  region  in  which  it  will  probably  be 
injurious  the  coming  season. 

IT   MIST   NOT    BE   CONFC8ED    WITH    THE   8HARPSHOOTER. 

In  Mexico  the  insect  is  known  to  cotton  growers  as  the  "picitdo,"  and  in  the 
lirow  nsville  region  cotton  planters  have  named  it  the  "sharpshooter."  From  the 
fact  that  this  term  has  been  rifled  by  the  Brownsville  cotton  planters,  some  confusion 
has  arisen  among  planters  living  farther  north,  and  many  of  them  have  supposed 
that  the  insect  is  nothing  but  a  species  which  has  been  known  for  many  years  in 


Fig.  2. — Map  showing  the  present  known  distribution  of  the  cotton-boll  weevil  in  Texas  Mid  Mexico. 

Texas,  and  to  which  this  same  popular  name  of  "sharpshooter"  has  been  applied. 
In  general,  it  may  be  said  that  whenever  bolls  or  squares  have  been  pierced  by  any 
insect,  and  wilt  in  consequence,  the  work  is  called  "sharpshooter  work."'  not  only 
in  Texas,  but  in  Louisiana,  Mississippi,  and  other  portions  of  the  cotton  belt. 
While  several  insects  are  engaged  in  this  so-called  sharpshooter  work,  the  most 
abundant  one  is  that  shown  at  fig.  3.  This  is  the  so-called  "glassy-winged  sharp- 
shooter" (Homaludisca  eoagulata),  belonging  to  an  entirely  different  group  of  insects 
from  the  Mexican  cotton-boll  weevil. 

The  glassy-winged  sharpshooter  has  been  present  in  Texas  cotton  fields  ever  since 
the  cultivation  of  cotton  began,  since  it  was  originally  not  a  cotton  insect,  but 
fed  upon  the  poplar  tree.  The  Mexican  cotton-boll  weevil  is  not  only  quite  a  dif- 
ferent insect,  but  it  is  a  far  more  dangerous  one.  It  is  much  more  abundant  and  its 
attacks  upon  bolls  and  squares  are  much  more  serious,  since  not  only  are  the  bolls 
punctured  with  the  beak,  as  is  the  case  with  the  glassy-winged  sharpshooter,  but 
eggs  are  inserted  and  larv;e  hatch,  which  feed  upon  the  interior  substance. 


s  \  II  RAI     H18TOK1     AM'    II  Mil  I". 

n„-  natural  bistorj  of  the  Mexican  cotton  boll  weevil  leasyel  Imperfei  tlj  known 
i,ut  m  in  as  can  no*  be  judged,  II  la  aa  follows: 

\\  ben  the  insects  Brel  appeal  the  egga  ure  deposited  in  the  squares  and  boll 
the  larva  batch  and  feed  en  the  interior  substance  of  the  i>u.l^  and  bolls.  I  In 
I.,,  (  ,  lometlmea  feed  on  the  i" 
lei  ioi  "i  the  seed,  leai  ing  onlj 
the  shell,  but  nsuallj  eal  seed  or 
Hbei  indifferently,  fhe  larva 
gradually  reachee  full  growth, 
Iki\  ing  l>>  tlii—  time  formed  aeall 
ol  sufficient  size  to  accommodate 
n-.lf,  and  in  this  it  pupates. 
The  cell  ia  nanallj  formed  next 
the  outer  wall  or  pericarp  of  the 
boll,  m>  thai  the  weevil,  when 
transformed,  has  only  to  make  its 
w.n  through  tlii—  wall  to  escape. 
In  issuing,  it  thus  leaves  a  small 
hole  in  the  pericarp,  whi<  li 
marks  th«'  cell  in  the  Infested 
lock  of  the  boll.  Aa  man;  a- 
eleven  larva:  have  been  found  in 
0U6  boll. 

Judging  from  the  habits  of  the 
allied  species,  Anthonomut 
earns,  and  allowing  tor  differ- 
ences in  eize  ami  climatic  con 
ditions,  the  duration  of  the  liiV- 
eycle  ia  probably  about  thirty 
days. 

In  the  neti  ly  infested  region 
in  Texas,  the  weevils  were  tii-t 
noticed  in  the  cotton  fields  from 
alxmt  the  middle  of  August  to 
the  last   of  September;   in  the 

newl)  infested  region  of  Coahuila,  a  month  earlier;  In  the  older  infested  regionsof 
Texan  Brownsville)  and  Coahuila  t  Hi  -rmanus  .  a-<  ai  ly  as  Ma\  to. Inn.-.  Approximate 
dates  of  their  first  appearance  in  newly  infested  regions  have  been  received  as 
follows:  Corpus  Christi  Nueces  region  i,  middle  of  Augusl ;  Beet  ille,  last  of  August 
and  find  of  September;  San  Diego,  t i r — t  of  September. 

Nothing  ia  known  positively  concerning  the  number  of  annual  broods,  bul  there 
were  probably  two  broods  in  the  newlj   infested  region,  and  in  the  older  <li-ti 
where  the  weevils  appear  in  May  and  Jnne,  there  mnsl   be  four  or  more  broods 
annuall]  • 

At  San  Juan  lUende,  Coahuila.  two  very  small  larva-  were  found  in  buds,  Novem- 
ber l'3.  and  at  Alice,  Tex.,  another  was  found  in  a  green  bud,  December  12.  This 
aeemB  t»  indicate  a  very  late  brood  If,  indeed,  the  broods  ar-'  at  all  regular.  1  gg 
laying  probably  goes  on  at  all  times,  so  that  the  broods  are  more  or  less  irregular. 

Foodplantt  and  kabitt  of  feeding  of  ih<  admit.— The  only  food  plant  bo  far  as  known 
is  cotton.  The  adults  Beem  to  feed  both  on  the  buds  and  lmiis.  and  throughoul  the 
season  as  long  as  the  weather  is  warm.  By  means  of  the  -mall  jaws  al  the  end  of  its 
beak,  the  wen  il  eats  through  the  skin  of  the  bud  or  boll,  making  a  small  hole  therein, 
BpecimenB  were  found  aa  late  as  December  1".  :;,;  miles  north  of  Brownsville,  with 
their  beaks  sunk  to  full  length  in  half-grown  green  holls.  apparently  feeding  on  th<- 
juices  within. 


i  Glass]  irlngedeharpshootei    a    idnlt  i  seen  from 

above  fr,  same,  side  viei  f  fore  wing    enlarged 

,;    antenna     e,  -  i  tlou  of  hind  tlb  II  ills    more 

enlarged    j  serrations  nl  ovipositor— still  more  eularj 


Extended  inquiry  show  that  the  weevils  always  remain  within  the  squares  or  on 
the  bulls,  and  never  Iced  Oil  the  leaves,  nor  are  they  ever  seen  on  the  latter. 

The  weevils  were  found  ai  Ban  Tomas,  and  just  north  of  Brownsville,  infesting 
fields  of  sea-island  cotton  as  badly  as  the  upland  variety.  There  seems  no  hope, 
therefore,  of  finding  a  variety  of  cotton  that  will  not  be  attacked  by  it. 

[f  the  weevil  has  another  food  plant,  it  will  probably  be  found  in  the  Monclova 
region  of  Coahuila.  No  wild  malvaceoua  plant  could  be  found  in  the  regions  visited, 
and  the  insect  was  not  found  on  auy  other  plant  than  cotton.  Information  obtained 
from  Monclova  states  that  the  insect  has  never  been  known  there  on  any  other  plant. 

Ovipoaition. — The  weevils  deposit  their  eggs  first  in  the  buds,  which  are  to  be 
found  within  the  squares.  When  the  buds  are  all  infested,  the  females  oviposit  in 
the  smallest  bolls,  then  in  the  next  largest,  until  all  are  attacked  that  arc  still  greeu. 
Judging  from  the  egg-laying  habits  of  the  genus,  the  female  makes  the  hole  in  the 
bud  or  boll  with  her  beak,  and  then  turning  around,  applies  the  tip  of  the  abdomen 
to  the  hole  and  deposits  an  egg  therein.  The  same  female  may  deposit  a  consider. 
able  number  of  eggs. 

Appearance  of  an  infested  field. — As  the  weevils  attack  first  of  all  the  buds  within 
the  squares,  these  usually  die  and  drop  off.  Therefore,  as  soon  as  a  field  becomes 
well  infested,  the  presence  of  the  insect  can  be  told  at  once  by  the  fact  that  few  or 
no  blooms  are  to  be  seen  on  the  plants.  A  field  may  be  in  full  bloom,  but  as  soon  as 
the  insect  gets  well  spread  over  it  and  accomplishes  its  work  hardly  a  bloom  will 
he  seen.  Soon  after  the  squares  are  attacked  they  mostly  turn  yellow  and  fall  to 
the  ground. 

Method  of  hibernation. — A  considerable  percentage  of  the  weevils  winter  over  in 
the  bolls,  in  the  cells  which  they  have  formed  therein,  either  as  transformed  weevils 
or  as  pupae,  or  perhaps  even  as  larvae.  That  they  may  sometimes  winter  as  larva) 
seems  proven  from  the  finding,  as  above  mentioned,  of  very  small  larva  from  the 
last  of  November  to  the  middle  of  December.  They  probably  winter  more  fre- 
quently as  pupa',  the  latter  having  been  found  in  the  bolls  up  to  the  middle  of 
December.  Newly  transformed  adults  were  found  plentifully  in  the  bolls  also  during 
late  fall  and  early  winter. 

But  there  are  many  other  individuals  belonging  to  earlier  broods  which  have 
issued  and  certainly  will  not  reenter  the  bolls  to  hibernate.  The  question  is,  Where 
do  these  hibernate?  In  San  Juan  Allcnde,  where  the  fields  arc  irrigated,  there  are 
many  cracks  in  the  earth,  caused  by  the  rapid  drying  of  the  soil  after  irrigating. 
Or.  a  cold  day  there  it  was  found  that  some  of  the  weevils  had  crawled  into  these 
cracks,  and  many  weevils  hibernate  in  such  cracks  and  under  clods  of  earth,  under 
leaves,  and  other  refuse. 

Weevils  were  also  found  in  Allcnde  on  the  cold  day  above  referred  to  (November 
23)  around  the  base  of  plants,  under  dry  fallen  leaves. 

In  fields  where  neither  cracks,  clods,  nor  fallen  leave*  exist,  as  happens  often  in 
southern  Texas,  where  the  plants  remain  green  until  late  in  winter,  many  weevils 
probably  winter  in  the  squares  and  under  the  leaves  :it  the  base  of  the  bolls.  At 
Alice  and  Benavides,  Tex.,  the  plants  were  perfectly  green  December  12,  there 
having  been  no  frost.  In  a  field  there,  on  that  date,  many  weevils  were  found  inside 
the  squares,  as  many  as  four  in  one  square;  also  at  the  bases  of  the  bolls.  Many 
were  neither  feedinguor  ovipositing,  but  were  perfectly  inactive.  The  squares  afford 
excellent  protection  to  the  weevils  in  cold  or  in  rainy  weather.  During  rainy 
weather  in  San  Juan  Allcnde  (November 28)  weevils  were  found  numerously  huddled 
in  the  squares  by  threes  and  fours. 

Live  weevils  were  found  at  Brownsville  inside  old  bolls  in  March,  showing  that 
the  insect  can  successfully  withstand  quite  severe  cold.  The  Weather  Bureau  records 
show  that  twice  during  the  past  winter  severe  frosts  were  experienced  all  over  the 
infested  region.  1'p  to  April  1.  although  diligent  search  was  made.no  hibernating 
beetles  were  found  under  leaves  or  in  cracks  in  the  ground  around  Brownsville. 


Mow     I  Ml     [N8K<    I     BPH1    M>- 

I  Le  ii.iiiii.il  spread  of  the  Iubci  t  i>\  flighl  is  slow  ,  and  it  is  questionable  «  < 
it  would  liav.  traveled  from  its  original  home  to  the  regions  now  infested  l>\  flight 
alone,  siuce  the  cotton-growing  regions  are  widelj  separated  hj  districts  in  w  1 1 i « ■  I « 

itMi  is  grown.     It  ruaj  have  other  i « * « » •  I  plants,  although,  as  previously  stated, 

Done  have  yel  bean  disoovered.    Should  if  In-  fonnd  thai  it  is  confined  t"  ootton,  it 

has  probablj  I □  carried  (rum  one  o  tton  growing  region  to  another  in  loadaof 

nngiunml  cotton  «  hen  being  taken  to  the  gin.  It  i>  bj  such  artificial  portage  thai  a 
large  share  of  its  future  spread  will  be  brought  about,  though  when  it  has  once 
entered  a  region  of  more  or  less  continuous  cotton  fields,  it  n  ill  spread  bj  tliuht  from 
i>ni'  field  to  another,  season  after  season. 

tXVKOTIOATION    I'.l     nil     I'l  r  \  I:  I  M l  s  l    "i      IURICCLTURI 

Twelve  years  ago  n  few  specimens  of  this  weevil  were  sent  to  the  Dopartment  ol 
■  11 1 1 11  r< ■  from  Mexico,  with  the  bare  statement  that  >i  was  known  to  feed  upon 
rot  ton.  No  details  were  given,  however,  which  indicated  that  an  investigation  was 
necessarj  In  the  summer  of  1894  it  was  sent  to  the  Department  by  several  cotton 
growers  in  rexas,  and  it  was  at  once  realized  thai  unless  checked  the  insect  would 
I.. »  ome  a  very  serious  enemy  to  the  cotton  crop  of  the  United  States,  An  investiga- 
tion was  immediately  begun.  \  special  agent,  Prof.  C.  H.Tyler  Townsend,  \\ :i h 
appointed  who  traveled  through  the  affected  regions  of  both  Texas  and  Mexico,  aud 

gathered  the  information  upon  which  this  circulai    is  based,  mosl  of  tli otter 

upon  the  natural  historj  and  habits  of  the  insect  being  given  in  his  own  words. 
He  has  been  temporarily  stationed  at  Brownsville,  Tex.,  for  the  purpose  of  stud)  ing 
the  life  history  of  the  insect  the  year  through,  in  the  hope  that  such  an  investiga- 
tion will  reveal  some  point  in  the  habits  of  the  species  which  w  ill  render  the  Bngges- 

ti f  some  practical  reined  \  possible.     The  at  tent  ion  of  the  Texas  state  authority  B 

has  been  called  to  the  Importance  of  the  insect,  and  to  the  apparent  danger  of  allow  ing 
n  to  increase  and  spread.  The  legislature,  during  its  present  session,  will  consider 
the  advisability  of  adopting  quarantine  and  restrictive  measures,  and  of  en  fori  i  nuc 
remedial  work. 

i:kmi  i>ii  - 

It  is  early  as  yet  to  Bnggest  remedies,  since  the  Department  has  not  had  an  oppor- 
tunity to  conduct  any  extensive  experiments.     8 uch  yet  remains  to  be  fonnd  out 

about  the  life  history  of  the  insect  that  anything  which  can  be  said  in  this  direction 
at  present  must  be  largelj  theoretical.  Living,  as  the  larva  does,  in  the  interior  of 
the  bud  or  boll,  it  can  not  be  reached  bj  ordinary  insecticides,  although  an  applica- 
tion of  pans  green  or  london  purple,  as  for  the  cotton  worm,  made  when  the  bolls 
begin  to  form,  may  kill  a  certain  percentage  of  the  adult  weevils,  since  these  feed, 

to  some  extent,  on  tile  outside  of  the  liolls. 

A   meat  de.ll  of  gOOd,  llowe\  er.  e  ill  l>e  done,  and  tile  insect   can  tie  largelj    led  need 

mi  nu  in  hers,  by  picking  all  affected  hoi  Is  at  the  time  of  the  cotton  picking  and  horn- 
ing them,  [f  each  cotton  picker  be  provided  with  a  separate  bag  in  w  bich  to  collect 
the  infested  bolls,  it  would  not  involve  a  great  amount  of  extra  labor  to  gather 

these  as  tin'  cotton  is  picked.  In  ice  ions  u  here  other  crops  can  be  grown,  it  will  he 
well  to  practice  rot  at  ion  of  crops,  and  not  grow  cotton  t  «  -ion  upon 

the  same  land. 
\:>]iro\  ed  : 

I..  «  >.  HOW  \l:l>. 

Chas,  W.  Dabni  \.  Jr.,  Entomologist. 

Ataiatani  Seen  tary. 
Washington,  D.  »'..  .i/o-.' 


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UNIVERSITY  OF  FLORIDA 


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